Kirkes' Handbook of Physiology Volume 1 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1885 Excerpt: ...Movements of the Nostrils and of the Glottis.--During the action of the muscles which directly draw air into the chest, those which guard the opening through which it enters are not passive. In hurried breathing the instinctive dilatation of the nostrils is well seen, although under ordinary conditions it may not be noticeable. The opening at the upper part of the larynx, however, or rima glottidis (Fig. 297), b dilated at each inspiration, for the more ready passage of air, and becomes smaller at each expiration; its condition, therefore, corresponding during respiration with that of the walls of the chest. There is a further likeness between the two acts in that, under ordinary circumstances, the dilatation of the rima glottidis is a muscular act, and itc contraction chiefly an elastic recoil; although, under various conditions, to be hereafter mentioned, there may be, in the contraction of the glottis, considerable muscular power exercised. Terms used to express Quantity of Air breathed.--Breathing or /../, // air, is the quantity of air which is habitually and almost uniformly changed in each act of breathing. In a healthy adult man it is about 30 cubic inches. Complemental air, is the quantity over and above this which can be drawn into the lungs in the deepest inspiration; its amount is various, as will be presently shown. Reserve air. After ordinary expiration, such as that which expels the breathing or tidal air, a certain quantity of air remains in the lungs, which may be expelled by a forcible and deeper expiration. This is termed reserve air. Residual air is the quantity which still remains in the lungs after the most violent expiratory effort. Its amount depends in great measure on the absolute size of the chest, but may be estimated at about 100..